1. Field of the Invention
The invention relates to a fan assembly, and in particular, to a fan assembly utilizing a centrifugal fan to generate an airflow to a channel structure, wherein the airflow flows out from the channel structure.
2. Description of the Related Art
A conventional household fan utilizes a motor to drive an axial-flow fan to rotate, and then an airflow is generated by the rotating axial-flow fan. The household fan has large blades to generate enough airflow. However, the larger blades have greater torque, and an extending direction and a rotating direction of the blade have an acute angle therebetween. Thus, it is very dangerous; especially if children touch the rotating blades.
To solve the above problem, US Patent App. publication No. 20090060710 discloses a fan 100 as shown in FIG. 1. An axial-flow fan 110 is disposed in a base 120, and air is drawn via an air inlet 121 of the side wall of the base 120. The air flows into an annular nozzle 130 along a flow path F1. Finally, the air flows out from the annular nozzle 130 and is discharged at the inner side of the annular nozzle 130 to flow along a flow direction D1.
Because the axial-flow fan 110 is disposed in the base 120, children cannot touch the axial-flow fan 110. Moreover, the inner side of the annular nozzle 130 is a hollow space, and thus the annular nozzle 130 will not block light due to the hollow space.
However, the above design has many disadvantages, and thus the exhaust efficiency of the fan 100 is very weak. In FIG. 1, the axial-flow fan 110 draws air along the axial direction and generates airflow along the axial direction. Since the blade of the axial-flow fan 100 is disposed downwardly, and the motor 111 is located between the blade and the annular nozzle 130, the airflow is guided upwardly to the annular nozzle 130. However, all of the components (such as the motor 111) of the axial-flow fan 110 will occupy almost all of the space inside of the base 120, and thus the airflow will flow in a narrow channel G. Thus, the exhaust efficiency is decreased because the airflow is blocked in the narrow channel G. Moreover, the air inlet 121 is disposed on the side wall of the base 120, and the direction of air flowing into the air inlet 121 via the side wall is perpendicular to the intake direction of airflow toward the annular nozzle 130. Thus, the intake efficiency is decreased.
Please also refer to FIG. 2, which is an enlarged view of the part A of FIG. 1. The annular nozzle 130 has an air outlet 132 disposed at the intake side 131, and thus the airflow flowing out from the air outlet 132 will flow from the intake side 131 to the exhaust side 133. In the figures, the airflow is blocked by the annular inner side wall of the annular nozzle 130, and the airflow volume of the air outlet 132 is decreased. Moreover, since the airflow of the annular nozzle 130 flows out from the air outlet 132 after rotation, the wind pressure and the exhaust airflow volume are decreased hugely. Thus, the exhaust efficiency of the fan 100 is decreased.